Abstract
Osteoglycin (OGN) is a leucine-rich proteoglycan that has been implicated in the regulation of glucose in animal models. However, its relationship with glucose control in humans is unclear. We examined the effect of high-intensity interval exercise (HIIE) and hyperinsulinemic-euglycemic clamp on circulating levels of OGN as well as whether circulating OGN levels are associated with markers of glycemic control and cardio-metabolic health. Serum was analyzed for OGN (ELISA) levels from 9 middle-aged obese men (58.1 ± 2.2 years, body mass index [BMI] = 33.1 ± 1.4 kg∙m(-2), mean ± SEM) and 9 young men (27.8 ± 1.6 years, BMI = 24.4 ± 0.08 kg∙m(-2)) who previously completed a study involving a euglycemic-hyperinsulinemic clamp at rest and after HIIE (4x4 minutes cycling at approximately 95% peak heart rate (HRpeak), interspersed with 2 minutes of active recovery). Blood pressure, body composition (dual-energy X-ray absorptiometry), and insulin sensitivity (hyperinsulinemic-euglycemic clamp) were assessed. Serum OGN was higher in the young cohort compared with the middle-aged cohort (65.2 ± 10.1 ng/mL versus 36.5 ± 4. 5 ng/mL, p ≤ 0.05). Serum OGN was unaffected by acute HIIE but decreased after the insulin clamp compared with baseline (~-27%, p = 0.01), post-exercise (~-35%, p = 0.01), and pre-clamp (~-32%, p = 0.02) time points, irrespective of age. At baseline, lower circulating OGN levels were associated with increased age, BMI, and fat mass, whereas higher OGN levels were related to lower fasting glucose. Higher OGN levels were associated with a higher glucose infusion rate. Exercise had a limited effect on circulating OGN. The mechanisms by which OGN affects glucose regulation should be explored in the future. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.